CN113771085B - Industrial robot joint structure - Google Patents
Industrial robot joint structure Download PDFInfo
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- CN113771085B CN113771085B CN202111281165.7A CN202111281165A CN113771085B CN 113771085 B CN113771085 B CN 113771085B CN 202111281165 A CN202111281165 A CN 202111281165A CN 113771085 B CN113771085 B CN 113771085B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J17/00—Joints
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J19/00—Accessories fitted to manipulators, e.g. for monitoring, for viewing; Safety devices combined with or specially adapted for use in connection with manipulators
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Abstract
A joint structure of an industrial robot comprises a joint body and a cable, wherein the joint body rotates around a joint rotating shaft; the joint body is positioned between the upper joint and the lower joint, a wire harness threading channel is arranged in the joint body, the wire harness threading channel is provided with an inlet and an outlet, and the axis of the wire harness threading channel is parallel to the joint rotating shaft; the cable is bent from the upper joint to enter the wire harness passing channel and form a first bent arc, and is bent to enter the lower joint and form a second bent arc; the cable is fixed on the starting point wire fixing piece and the end point wire fixing piece respectively and meets the requirement that the eccentricity e is less than or equal to 0 (the actual threading diameter D/2 is greater than or equal to safety factor K) -the diameter D/2 of the cable, the eccentricity e is the minimum distance from the central line of the cable to the joint rotating shaft, and the actual threading diameter D is the diameter of a wiring harness threading channel. Compared with the prior art, the joint structure of the industrial robot can improve wiring efficiency.
Description
Technical Field
The invention relates to the technical field of industrial robots, in particular to a joint structure of an industrial robot.
Background
Industrial robots are becoming an indispensable part of modern society because they are adaptable to high-intensity work and have high motion accuracy. Most of the existing industrial robots have a plurality of joints and each joint is driven by electric power, so cables for power supply and control are distributed in each joint of the robot, and cable arrangement is an important issue in industrial robot design.
In the prior art, most of cable arrangements between joints of an industrial robot are based on experience, and routing paths are designed according to routing of other machine types and robot structures. Whether main consideration has enough space to let the cable pass through, whether the cable can take place wearing and tearing scheduling problem with other spare parts in the course of the work, fixes the cable through setting up solidus spare. After the cable is fixed, operating the industrial robot for a period of time and checking whether the cable is abraded, and if the cable is not abraded, finishing the cable setting; and if the abrasion occurs, searching the reason of the abrasion, redesigning the routing, detaching the cable and the wire fixing piece, and rewiring.
It can be seen from the above that, the cable installation method in the prior art is mainly performed in a static wiring manner, that is, pre-wiring is performed in a state where the joint does not move, and then confirmation is performed in a state where the joint moves, so that it is necessary to repeatedly switch the state of the industrial robot to perform debugging and obtain a final wiring scheme. Therefore, the cable arrangement is time consuming and inefficient. Especially, most of the existing industrial robots adopt the premise of internal wiring, and the robots are inevitably assembled and disassembled for many times in the repeated debugging process, so that the difficulty is brought to debugging.
Disclosure of Invention
In view of the above, an object of the present invention is to provide an industrial robot joint structure to reduce repeated debugging of wiring, thereby improving wiring efficiency.
The technical scheme adopted by the invention is as follows:
a joint structure of an industrial robot comprises a joint body and a cable, wherein the joint body rotates around a joint rotating shaft; the joint body is positioned between a previous joint and a next joint, a wiring harness threading channel is arranged in the joint body, an opening of the wiring harness threading channel, which is close to the previous joint, is an inlet, an opening of the wiring harness threading channel, which is close to the next joint, is an outlet, and the axis of the wiring harness threading channel is parallel to the joint revolving shaft; the cable is bent from the upper joint to enter the wire harness passing channel and form a first bent arc, and is bent to enter the lower joint and form a second bent arc; the cable is fixed on the starting point wire fixing piece and the terminal point wire fixing piece respectively, so that the requirement that an eccentricity e is less than or equal to 0 (an actual wire passing diameter D/2 x safety factor K) -a cable diameter D/2 is met, the eccentricity e is the minimum distance from a central line of the cable in the wire harness wire passing channel to the joint rotating shaft, and the actual wire passing diameter D is the diameter of the wire harness wire passing channel.
Compared with the prior art, the joint structure of the industrial robot is provided with the cables according to the space structure of the industrial robot and the position relation between the wire passing channel and the joint rotating shaft, so that a space is reserved for cable rotating motion, the condition of rewiring caused by abrasion of wire harnesses in dynamic motion is reduced, and the wiring efficiency is improved.
Further, factor of safety K with cable diameter d is directly proportional, and the size is more than 1.1 and below 2 to ensure that the cable can pass through this joint smoothly and do not occupy too big space.
Further, the cable also needs to satisfy a corner radius reservation coefficient k1, where the cable diameter d ≦ the cable bending radius r ≦ the actual maximum operating turning height h; the reserved coefficient k1 of the corner radius is more than 1.1; the cable bending radius r is the bending radius of the second bending arc axis; the cross section of the wire harness threading channel is circular, and the actual operation maximum turning height h is the maximum diameter of the cross section of the wire harness threading channel, so that the wire harness threading channel is prevented from being contacted with the wire harness threading channel due to the fact that the bending radius r of the cable is too large or too small.
Further, when the arm spread of the industrial robot is less than 1 meter, the reserved coefficient k1 of the corner radius is 2; when the arm spread of the industrial robot is less than 2 meters, the reserved coefficient k1 of the corner radius is 4; when the arm span of the industrial robot is more than 2 meters, the reserved coefficient k1 of the corner radius is 6 so as to meet the wiring requirements of different industrial robots.
Further, the fixed position of the cable on the starting point wire fixing piece is a wire fixing starting point, and the fixed position on the end point wire fixing piece is a wire fixing end point; in the direction parallel to the joint rotation axis, the distance L = r ' sin β 1+ L ' + rsin β 2-L "cos β 2, r ' from the solid line starting point to the solid line ending point is the axial bending radius of the first bending circular arc, and r is the axial bending radius of the second bending circular arc; l 'is the length of a straight line section between the first curved circular arc and the second curved circular arc in a projection in a direction parallel to the joint rotation axis, and l' is the distance from the axis terminal point of the second curved circular arc to the line fixing terminal point; β 1 is the turning angle of the first curved arc and β 2 is the turning angle of the second curved arc, thereby determining the fixed position of the cable in the joint.
Further, when the eccentricity e is equal to 0, the length of the second curved arc is
When the eccentricity e is not equal to 0, the length of the second bending arc is
Theta is the maximum rotation angle of the joint body rotating around the joint rotation shaft in actual work, so that the cable is not easy to fall off in the movement process.
Further, when the industrial robot joint structure is in operation, the relative torsion angle alpha of the cable is smaller than the limit value of the cable torsion, so as to prevent the wire harness from exceeding the limit range of the rotation of the wire harness.
Further, the relative torsion angle of the cable
L is the distance from the starting point of the fixed line to the end point of the fixed line, M is the allowable torque when the motor which drives the joint structure of the industrial robot to rotate is started and stopped at the maximum speed, mu is the Poisson ratio, E is the elastic modulus, and the relative torsion angle alpha is related to the allowable torque during movement, thereby meeting the requirement of the dynamic movement process of the joint.
For a better understanding and practice, the invention is described in detail below with reference to the accompanying drawings.
Drawings
FIG. 1 is a schematic flow chart of the wiring method between joints of an industrial robot according to the present invention;
fig. 2 is a schematic structural view of a joint of an industrial robot according to an embodiment of the present invention;
FIG. 3 is a schematic view of the joint of FIG. 2 showing the wiring harness;
FIG. 4 is a schematic view of the structure of the wiring harness of FIG. 2;
fig. 5 is a schematic view of a joint structure obtained by the installation of the internal wiring method between joints of the industrial robot in one embodiment.
Detailed Description
Because the actual use environment of each joint of the industrial robot is dynamic and each joint moves relatively, the method for internally wiring the joints of the industrial robot analyzes the dynamic parameters of each joint in advance and internally wiring the joints according to the dynamic parameters, thereby reducing the number of times of adjusting wiring.
Specifically, referring to fig. 1 to 4, when cables are routed inside, a wire harness 4 composed of a plurality of cables is bent and turned from a previous joint to a certain joint and then from the certain joint to a next joint, and the wire harness 4 is bent and penetrates through the entire industrial robot. For a joint, the wire harness 4 is generally positioned by arranging wire fixing members at the inlet and the outlet of the joint.
When the joint is arranged, one end of the wiring harness 4 is fixedly arranged near the inlet of the wire passing channel 2 in the joint through the wire fixing piece, then the wiring harness 4 is pulled to one side of the next joint along the wire passing channel 2 and penetrates through the next joint, the other end of the wiring harness 4 is fixedly arranged near the outlet of the wire passing channel 2 through the wire fixing piece, and the wiring harness 4 is limited in the joint by the two wire fixing pieces. Therefore, along the direction of the wire harness 4, the wire fixing point near the entrance of the wire passing channel 2 in the same joint is used as the wire fixing starting point in the joint, the wire fixing point near the exit of the wire passing channel 2 is used as the wire fixing end point, the wire fixing end point is used as the wire fixing starting point of the next joint, and the wire harness 4 is fixed by analogy in sequence. That is, the origin of the solidus of the other joint than the base and the end can be calculated when the wire harness is set up for the joint above it, i.e. the origin of the solidus is known for a certain joint, and the endpoint of the solidus of the joint can be determined by the method for setting up the inter-joint internal cable of the industrial robot according to the present invention.
Specifically, in the present embodiment, the joint shown in fig. 2 includes a body 1, a wire passage 2, a motor 3, and a wire harness 4. Wherein the wire passage 2 is arranged in the body 1 and the extending direction is vertical to the horizontal plane. The wire harness 4 is formed by bundling a plurality of power supply cables and control cables. The string passing channel 2 is provided with an inlet 21 communicating with the previous joint and an outlet 22 leading to the string passing channel (not shown) of the next joint. The wire harness 4 horizontally passes through the inlet 21 and is bent into the wire passage 2, and a first wire fixing member (not shown) is provided according to the structure to fix the wire harness to the vicinity of the inlet 11. The wiring harness 4 is supported by the second wire fixing member 5 and is fixed in the vicinity of the outlet 12 under bundling with a binding tape.
Referring to fig. 3, the axes of the wire harnesses 4 are located in the same plane through projection. And in the direction from the inlet 21 to the outlet 22, the wire harness 4 is bent to enter the wire passing channel 2 and form a first bent circular arc C1, a binding belt is arranged on the first wire fixing piece and is used for binding the wire harness 4 at the starting point of the first bent circular arc C1, and the axial starting point of the first bent circular arc C1 is set as a wire fixing starting point J. The radius of the first curved circular arc C1 is r ", and the size of r" is adjusted so that the axis of the wire harness 4 is substantially coincident with the center line a of the wire passage 2. The corner of the first curved arc C1 is a first included angle β 1.
An arc formed by bending the wire harness 4 out of the wire passage 2 to enter the next joint is a second bent arc C2, and a binding tape is provided on the second wire fixing member 5 and binds the wire harness 4 with a fixed position having a certain distance from the terminal end of the second bent arc C2. And arranging the second bending arc C2 axis and the cable tie, wherein the fixed position of the wire harness 4 is a wire fixing terminal point K. Since the position of the fixed line starting point J is determined by calculation when the last joint is wired, and therefore is a known point, the position of the fixed line end point K is determined by the industrial robot inter-joint internal wiring method of the invention to fix the cable 4 in the joint, comprising the following steps:
s10: and acquiring the structure of the industrial robot and setting a cable overall wiring scheme.
The structure comprises the number of joints, the motion mode of each joint, the components, parts and structures of each joint, the shape of each joint wire passing channel, the shape and the connection relation of each component and the like.
The general routing scheme includes the running direction of the cable, parts and the like passing through.
S20: a first wire fixing member is arranged beside the inlet 21, and the wire harness 4 is bent into the wire passing channel 2 after the wire harness 4 is bundled on the first wire fixing member by a first binding belt 6, so that the first bending circular arc C1 is formed and the starting point of the axis of the first bending circular arc C1 is taken as a wire fixing starting point J. The first cable tie 6 surrounds the outer side of the wire harness 4 and projects along the radial direction of a ring formed by the first cable tie, and the thread fixing starting point J is superposed with the ring formed by the first cable tie 6. And respectively measuring and obtaining the diameter D of the wire harness 4, the actual wire passing diameter D and the allowable torque M' when the motor driving the joint to rotate is started or stopped at the maximum speed.
The wire harness diameter d is the maximum diameter of the wire harness 4 passing through the joint.
The diameter D of the actual rotating shaft is the diameter of the wire passing channel 2; if the inside of the wire passing channel is provided with the wire passing pipe, the diameter of the wire passing pipe is the same as the diameter of the wire passing pipe.
The allowable torque M' is designed according to the actual working requirement of the industrial robot and is the torque when the industrial robot starts and stops at the maximum speed.
In the present embodiment, the harness diameter D =18mm, the actual wire diameter D =27mm, and the allowable torque M' =234Nm at the maximum speed start and stop.
S30: calculating to obtain a value range of the eccentricity e, wherein the value range of the eccentricity e should satisfy (the wire harness diameter D/2+ e) × the safety coefficient K ≦ the actual wire passing diameter D/2, and obtaining by sorting: 0 ≦ e ≦ (actual wire diameter D/2 × safety factor K) -the harness diameter D/2.
Wherein the eccentricity e is the minimum distance between the central line A of the wire passage 2 and the joint rotating shaft B.
In an ideal state, the axis of the wire harness 4 is parallel to the extending direction of the wire passing channel 2, the center line A of the wire passing channel 2 is overlapped with the joint rotating shaft B, and the axis of the wire harness 4 is overlapped with the joint rotating shaft B after being fixed. However, in practical operation, due to the limitation of the structural space, the center line a of the wire passage 2 and the joint rotation axis B are often not coincident, and the minimum distance between the joint rotation axis B and the harness center line a is the eccentricity e.
The eccentricity e is controlled within a reasonable range, so that the joint is compact in structure, and the influence of centrifugal force on the wire harness 4 in the rotation process is reduced.
As can be seen from fig. 3, the eccentricity e and the harness diameter D are constrained by the actual wire passing diameter D, i.e., the harness diameter D/2 is constrained by the actual wire passing diameter D/2. This is because, in the design, on one hand, a sufficient wire passing space is ensured, and even if the wire harness 4 shakes due to the action of centrifugal force during the rotation of the joint, the wire harness 4 does not contact with the inner wall of the wire passing channel 2, so that the abrasion of the wire harness 4 is reduced, and therefore, the sum of the wire harness diameter D/2 and the eccentricity e cannot be too large relative to the actual wire passing diameter D; on the other hand, it is ensured that the joint structure cannot be too large, so that the sum of the wire harness diameter D/2 and the eccentricity e cannot be too small relative to the actual wire passing diameter D. Therefore, (D/2 + e) safety factor K ≦ actual line-passing diameter D/2.
The safety coefficient K is an empirical value and is in direct proportion to the diameter d of the wire harness, and the value range is 1.1-2. Preferably, the safety factor K is 1.2, so as to ensure that the wire harness 4 can smoothly pass through the joint without occupying too much space.
In this embodiment, since the wire harness diameter D =18mm and the actual wire passing diameter D =27mm, the safety factor K is =1.2, that is, (18/2 + e) × 1.2 ≦ 13.5, and the eccentricity e obtained by trimming has a value range of 0 ≦ e ≦ 2.25mm.
S40: obtaining a value range of the cable bending radius r, wherein the value range of the cable bending radius r should meet a corner radius reserved coefficient k1, and the wire harness diameter d is less than or equal to the cable bending radius r is less than or equal to the actual maximum operation turning height h.
Wherein, the cable bending radius r is the bending radius of the axis of the second bending arc C2 formed when the wire harness 4 enters the next joint.
The corner radius reserve factor k1 is set in order to ensure sufficient space for the wire harness 4, and the corner radius reserve factor k1 is generally 1.1 or more. And as the more the arm spread of the robot is, the more the power is required, the more cables are required and the diameter of a single cable is larger, so that the diameter of the wire harness 4 is larger, and therefore the required space is larger, and the corner radius reserved coefficient k1 is proportional to the wiring space to ensure that enough space is provided for bending the circular arc. Preferably, the corner radius reserved coefficient k1 is more than 2; the number k1 of the small robot with the arm spread of less than 1 m is 2; the medium robot k1 with the arm spread of less than 2 meters is 4; the large robot k1 with an arm spread of more than 2 meters is 6. Particularly, if the limitation of the structural space is met, when the reserved corner radius coefficient k1 cannot meet 1.1 or more, the requirement of the wire passing space can be met by adjusting the cross section shape of the wire harness according to the cross section shape of the wire passing space, for example, if the length and width of the cross section of the wire passing channel at the bend are large, the wires forming the wire harness 4 can be formed by adjusting the wires forming the wire harness 4 to be in a tiled mode in which the wires are sequentially and tightly arranged along the radial direction of the wire passing channel, and the value range of the bending radius r of the wires at the time should meet the requirement that the diameter d of the wire harness is less than or equal to the bending radius r of the wires is less than or equal to the maximum actual operating turning height h.
Along the extending direction of the wire harness 4, the wire passage 2 is divided into a plurality of cross sections which are perpendicular to the axis of the wire harness 4. The actual maximum running turning height h is the maximum width of each cross section forming the wire passing channel 2 and can be obtained by measuring a joint structure. For example, if the cross-section of the wire passage 2 is a circle with different diameters, the actual maximum turning height h is the diameter of the circle with the largest area in each cross-section. If the cross section of the wire passing channel 2 is a rectangle with different shapes, the actual operation maximum turning height h is the longest long side value in each rectangle.
The abrasion of the wire harness 4 caused by contact with a joint body due to the fact that the cable bending radius r is too large or too small is prevented by determining the value range of the cable bending radius r of the second bending circular arc C2.
In this embodiment, the wire harness diameter d =18mm, the corner radius reservation coefficient k1=1.1, the cross section of the wire passage 2 is circular, and the actual maximum operating turning height h is 35mm. Thus 1.1 x 18 r ≦ 35, i.e. 20mm ≦ r ≦ 35mm.
S50: and selecting the eccentricity e and the cable bending radius r according to the value range calculated in the steps S30 and S40, and bending the wire harness 4 to form the second bending arc C2.
In the present embodiment, the eccentricity e =0 and the cable bending radius r =20mm are selected, and the second wire fixing member is disposed at the outlet 22 of the joint.
S60: and arranging the second wire fixing piece, determining the position of the wire fixing end point K and arranging a second bandage 7 to fix the wiring harness 4 on the second wire fixing piece.
In the direction away from the outlet 22, a tangent is provided to the axis of the second curved circular arc C2, along which the wire bundle 4 extends to the next joint. The included angle between the tangent line and the axis of the wire passing channel 2 is a second included angle beta 2, and the second included angle beta 2 is adjusted to ensure that a certain gap is formed between the outer side of the wire harness 4 and other parts. Preferably, the clearance is the wire harness diameter d/2 or 3 to 5mm; if the diameter d/2 of the wire harness is larger than 5mm, the gap is the diameter d/2 of the wire harness; if the wire harness diameter d/2 is less than 3mm, the clearance is any value of 3 to 5mm. And the tangent point of the tangent line and the axis of the second curved circular arc C2 is the terminal point of the second curved circular arc C2. And the distance between the end point k of the fixed line and the end point of the second curved circular arc C2 is 10 to 15mm along the tangent line, so that the bundling of the binding belt is facilitated.
In this embodiment, the distance l =15mm from the end point of the second curved arc C2 to the end point K of the fixed line.
Thus far, the positions of the fixed points at both ends of the wire harness 4 are determined. The fixed point at one end is the fixed line starting point J, and the fixed point at the other end is the fixed line terminal point K. Meanwhile, the line fixing end point K is a known point and is used as the line fixing starting point of the next joint.
S70: and calculating according to the positions of the fixed line starting point J and the fixed line end point K to obtain the torsion length L. The torsion length L is the distance from the fixed line starting point J to the fixed line end point K in the direction of the joint rotating shaft B.
The wire harness 4 is twisted along with the joint rotating around the joint rotating shaft B, so that the twisting direction is parallel to the joint rotating shaft B, that is, the twisting length L is the distance from the thread fixing starting point J to the thread fixing end point K in the direction of the joint rotating shaft B.
As shown in fig. 3, the wire harness 4 is placed in an orthogonal coordinate system with the central axis a of the wire passage 2 as the Y-axis. And measuring and obtaining a distance L = r ' sin beta 1+ L ' + rsin beta 2-L ' cos beta 2 from the fixed line starting point J to the fixed line end point K on the wire harness 4, and respectively measuring the sizes of L ', L ', beta 1 and beta 2 to obtain the size of the torsion length L.
In this example, the calculated twist length L was 200mm.
S80: and calculating and obtaining the reserved cable length allowance a of the cable in the second bending arc C2 according to the eccentricity e, the cable bending radius r, the torsion length L and the joint rotation angle theta. The rotation angle theta is the maximum rotation angle of the joint rotating around the rotation axis B in actual work and is obtained by design according to the actual working state of the industrial robot. When theta is larger than or equal to 180 degrees, the calculation is carried out according to 180 degrees, and when theta is smaller than 180 degrees, the calculation is carried out according to the actual revolution angle. During calculation, according to the position geometric relationship among the wire harness central line, the joint rotating shaft and the cable cross section when the cable rotates, the following two conditions are divided:
1. when the centre line a of the wire harness 4 coincides with the pivot axis B of the joint, i.e. the eccentricity e is equal to 0:
a) A required length 1 at a second curved arc C2 of the wire harness 4 0 = the cable bend radius r;
b) Required length 1 of cable located at outermost side of wire harness 1 Comprises the following steps:
as shown in fig. 4, the length 1 of the axis of the fixed cable in the static state is generally in the second arc of curvature C2 0 The fixing is performed for the standard, so that the outermost cable of the wire harness 4 is in a tight state, so that the outer cable is easily pulled and loosened in a dynamic state, and therefore, the length of the second bending arc C2 should be l 1 I.e. a reserved cable length margin a =1 should be reserved 1 -1 0 。
In this embodiment, the eccentricity e is equal to 0, the cable bending radius r is 20mm, the harness diameter d is 18mm, and the rotation angle θ =340 ° >180 ° is θ =180 °.
Then 1 0 ＝r＝20mm，
The reserved cable length margin a =22-20=2mm
2. When the centerline a of the wire harness 4 does not coincide with the joint rotation axis B and the eccentricity e is not equal to 0:
a) Length 1 of the axis of the second curved arc C2 2 Comprises the following steps:
b) The desired length 1 at the outermost side of the second curved arc C2 3 Comprises the following steps:
at this time, the reserved cable length margin a =1 of the second curved arc C2 3 -1 2 。
S90: acquiring a relative torsion angle alpha of the cable, judging whether the relative torsion angle alpha of the cable is smaller than a safety angle value, and if the relative torsion angle alpha of the cable is smaller than the safety angle value, performing the next step; and if the angle is not less than the safety angle value, reselecting the cable material.
When the relative torsion angle α is dynamic, the wire harness 4 is twisted with the joint at an actual angle.
The safety angle value is a limit value of the torsion of the wire harness 4, is related to the material and the cross section shape of the cable, and is provided by a cable manufacturer.
Calculating the torsion moment M borne by the cable according to a mechanical theory formula, wherein the maximum value of the torsion moment M borne by the cable is the allowable torque M 'when the motor rotating the joint is started and stopped at the maximum speed, so that the allowable torque M' is adopted for calculation during calculation:
M＝αGI p /L
where α is the relative twist angle in rad. G is the cable shear modulus. I is p Is the polar moment of inertia of the cable. L is the twist length.
The cable shear modulus G can be calculated by the following formula:
wherein E is the elastic modulus, mu is the Poisson's ratio, and the two are related to the cable material and can be obtained according to the material inspection manual.
Regarding the wire harness 4 as a solid circular section I p And the polar inertia moment is calculated according to a formula for calculating the polar inertia moment in theoretical mechanics:
subjecting the cable shear modulus G and the cable polar moment of inertia I p Substituting the calculation formula into the calculation formula of the torsional moment M borne by the cable and arranging to obtain the theoretical relative rotation angle alpha of the cable:
in the present embodiment, the twist length L =200mm; the torsional moment M = the allowable torque M ', and the allowable torque M' =234Nm; the cable is made of a copper core wire material with a six-core wire and a stainless steel shielding net, the elastic modulus E is 117GPA, the Poisson ratio mu is 0.34, the diameter d of the wire harness is =18mm, and the safety angle value =10 degrees provided by a manufacturer are obtained through table lookup
If the requirement is met, the next step can be carried out.
S100: and the wire harness 4 is fixed by tightening the second cable tie 7 after the reserved cable length allowance a is reserved, then the wire harness of the next joint is fixed, and then the wire harness 4 is sequentially fixed to other joints of the industrial robot and then is trial-run for a period of time.
Preferably, the run time is 3 days of continuous operation.
S110: detecting whether the wiring harness 4 breaks down or not, and if not, finishing the setting of the wiring harness 4; if yes, repeating the steps S20 to S90, and reselecting the parameters such as the wire harness diameter d, the material of the wire harness 4, the cross section shape of the wire harness 4, the allowable torque M' of the motor and the like, and carrying out calculation and evaluation again until no fault occurs.
Through the above steps, a robot joint may be obtained, as shown in fig. 5, including a joint body 10, a driving motor 20, a speed reducer 30, a start-point wire fixing member 40, a finish-point wire fixing member 50, and a cable 60. The motor drive 20 drives the speed reducer 30 to rotate, the joint body 10 rotates coaxially with an output shaft of the speed reducer 30, a wire harness passing channel 110 is arranged in the joint body 10, the wire harness passing channel 110 is a tubular channel and is respectively communicated with a passing channel of a previous joint (not shown) and a passing channel of a next joint 100, an opening of one end of the wire harness passing channel 110 close to the previous joint is an inlet of the wire harness passing channel 110, and an opening of one end of the wire harness passing channel 110 close to the next joint 100 is an outlet of the wire harness passing channel 110. The starting point wire fixing piece 40 is fixed with the joint body 10 and close to the inlet of the wire harness passing channel 110, and the terminal point wire fixing piece 50 is fixed with the next joint and close to the outlet of the wire harness passing channel 110. The cable 60 may be bundled by a plurality of cables or may be composed of a single cable, the cable 60 is bent to pass through the outlet of the harness passage 110 and enter the next joint 11, and the minimum distance between the center line of the cable 60 and the pivot axis of the joint body 10 is an eccentricity e. The bending radius of the cable 60 passing through the outlet of the wire harness passing channel 110 in a bending manner is a cable bending radius r, and the pipe diameter of the passing channel 110 is D. The starting point wire fixing piece 40 supports the wire harness 60, the terminal point wire fixing piece 50 supports the cable 60, and enables 0 < e > (actual wire passing diameter D/2 < safety factor K) -D/2, and a corner radius reserved coefficient K1 < joint wire harness diameter D < cable bending radius r < actual operation maximum turning height h.
Further, the fixing point of the cable 60 on the starting point wire fixing member 40 is a wire fixing starting point J, the fixing point on the terminal point wire fixing member 50 is a wire fixing terminal point K, the distance L = r ' sin β 1+ L ' + rsin β 2-L "cos β 2, r ' from the wire fixing starting point J to the wire fixing terminal point K in the direction parallel to the joint rotation axis B is a bending radius of the first bending circular arc C1 axis, and r is a bending radius of the second bending circular arc C2 axis; l 'is the length of a straight line segment positioned between the first curved circular arc C1 and the second curved circular arc C2 projected in the direction parallel to the joint rotation axis B, and l' is the distance from the axis terminal point of the second curved circular arc C2 to the line fixing terminal point K; β 1 is a turning angle of the first curved arc C1, and β 2 is a turning angle of the second curved arc C2.
Further, in order to ensure that the cable does not loosen, the center line of the curved section of the cable 60, which is curved to pass through the outlet of the wire passing channel 110 under the support of the terminal wire fixing element 50, should satisfy the following conditions: the eccentricity e is equal to 0, and the length of the second curved arc C2 is
When the eccentricity e is not equal to 0, the length of the second bending arc C2 is
Theta is the maximum rotation angle of the joint around the rotation axis B in actual work.
Further, the cable material of the cable 60 is selected such that the relative torsion angle α is smaller than the safety angle value, wherein the relative torsion angle α is calculated according to the following formula:
wherein L is the distance from the starting point of the fixed line to the end point of the fixed line, M' is the allowable torque when the motor driving the joint structure of the industrial robot to rotate is started and stopped at the maximum speed, mu is the Poisson ratio, and E is the elastic modulus.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.
Claims (6)
1. A joint structure of an industrial robot comprises a joint body and a cable, wherein the joint body rotates around a joint rotating shaft; the joint body is positioned between a previous joint and a next joint, a wiring harness threading channel is arranged in the joint body, an opening of the wiring harness threading channel, which is close to the previous joint, is an inlet, an opening of the wiring harness threading channel, which is close to the next joint, is an outlet, and the axis of the wiring harness threading channel is parallel to the joint revolving shaft; the cable is bent from the upper joint to enter the wire harness passing channel and form a first bent arc, and is bent to enter the lower joint and form a second bent arc; the method is characterized in that: the cable is fixed on the starting point wire fixing piece and the end point wire fixing piece respectively, so that the requirement that 0 ≦ e ≦ K × D/2-D/2 is met, wherein e is an eccentric distance, D is an actual wire passing diameter, D is a cable diameter, and K is a safety coefficient; the eccentricity e is the minimum distance from the central line of the cable in the wire harness threading channel to the joint revolving shaft, and the actual threading diameter D is the diameter of the wire harness threading channel;
the cable also meets the reserved coefficient k1 of the corner radius, and the cable diameter d ≦ the cable bending radius r ≦ the actual operation maximum turning height h; the reserved coefficient k1 of the corner radius is more than 1.1; the cable bending radius r is the bending radius of the second bending arc; the cross section of the wire harness threading channel is circular, and the actual operation maximum turning height h is the maximum diameter of the cross section of the wire harness threading channel;
the fixed position of the cable on the starting point wire fixing piece is a wire fixing starting point, and the fixed position of the cable on the end point wire fixing piece is a wire fixing end point; in the direction parallel to the joint rotation axis, the distance L = r ' sin β 1+ L ' + rsin β 2-L "cos β 2, r ' from the solid line starting point to the solid line ending point is the bending radius of the first curved circular arc, and r is the bending radius of the second curved circular arc; l 'is the length obtained by projecting a straight line segment between the first curved arc and the second curved arc in the direction parallel to the joint rotation axis, and l' is the distance from the terminal point of the second curved arc to the terminal point of the fixed line; β 1 is a turning angle of the first curved arc, and β 2 is a turning angle of the second curved arc.
2. The industrial robot joint structure according to claim 1, characterized in that: the safety factor K is in direct proportion to the diameter d of the cable, and the size of the safety factor K is more than 1.1 and less than 2.
3. The industrial robot joint structure according to claim 1, characterized in that: when the arm spread of the industrial robot is less than 1 meter, the reserved coefficient k1 of the corner radius is 2; when the arm spread of the industrial robot is less than 2 meters, the reserved coefficient k1 of the corner radius is 4; and when the arm spread of the industrial robot is more than 2 meters, the reserved coefficient k1 of the corner radius is 6.
4. The industrial robot joint structure according to claim 1, characterized in that: when the eccentricity e is equal to 0, the length of the second curved arc is
When the eccentricity e is not equal to 0, the length of the second bending arc is
Theta is the maximum rotation angle of the joint body rotating around the joint rotation shaft in actual work.
5. The industrial robot joint structure according to claim 1, characterized in that: when the industrial robot joint structure works, the relative torsion angle alpha of the cable is smaller than the limit value of the torsion of the cable.
6. An industrial robot joint structure according to claim 5, characterized in that: relative torsion angle of the cable
L is the distance from the starting point of the fixed line to the end point of the fixed line, M' is the allowable torque when the motor driving the joint structure of the industrial robot to rotate is started and stopped at the maximum speed, mu is the Poisson ratio, and E is the elastic modulus.
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| CN202111281165.7A CN113771085B (en) | 2021-11-01 | 2021-11-01 | Industrial robot joint structure |
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| CN112809742A (en) * | 2021-01-26 | 2021-05-18 | 浙江禾川科技股份有限公司 | Inside line joint and arm of crossing |
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| WO2009069389A1 (en) * | 2007-11-26 | 2009-06-04 | Kabushiki Kaisha Yaskawa Denki | Vertical multi-joint robot |
| US8602456B2 (en) * | 2010-12-09 | 2013-12-10 | Harris Corporation | Ball joint having a passageway for routing a cable therethrough |
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| JP2005047006A (en) * | 2004-10-25 | 2005-02-24 | Nabtesco Corp | Turning part structure of robot or the like |
| CN107920866A (en) * | 2015-08-20 | 2018-04-17 | 索尼奥林巴斯医疗解决方案公司 | Medical observation device and medical viewing system |
| CN108436966A (en) * | 2018-03-20 | 2018-08-24 | 厦门宏发工业机器人有限公司 | A kind of protection of transition wire for rotating coaxially joint of interior cabling industrial robot |
| CN109397267A (en) * | 2018-12-13 | 2019-03-01 | 南京熊猫电子股份有限公司 | Industrial robot compact pedestal and its cable method for arranging |
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